The present invention relates to a treatment process for reducing the pollutant concentration in waste gases, particularly by oxidation.
A known process for the oxidative decomposition of pollutants in exhaust gas is thermal afterburning (TAB).
A series of fundamental investigations of the TAB of pollutants shows that in the majority of applications, the TAB-installation must be designed in accordance with the oxidation conditions of the intermediate products (secondary pollutants), particularly carbon monoxide (CO) and that correspondingly high operating temperatures, substantially in excess of 750.degree. C., are required.
In particular, in the case of pollutants of Emission Class III of the Technische Anleitung zur Reinhaltung der Luft (Technical Guidelines for the Purification of Air)--hereafter "TALuft", the permissible residual concentrations of the primary pollutants (300 mg/m.sup.3) is attained already at temperatures between about 500.degree. and 600.degree. C., while a permissible CO residual concentration of a maximum of 100 mg/m.sup.3 (normal m.sup.3) is attained only at temperatures above 800.degree. C.
These conditions become more severe in actual practice when deposits are precipitated over time on the wall of combustion chambers, thus inhibiting the CO oxidation and consequently requiring even higher temperatures for the treatment of the exhaust gases.
In order to eliminate secondary pollutants, it is thus necessary to treat the exhaust gas at substantially higher temperatures than those required for the elimination of the primary pollutants. This requirement renders the conventional treatment of exhaust gases significantly more expensive, both from a technical and an economical standpoint.